Optical discs, including CD, LD, VCD, DVD, CD-R, and DVD-R, are thin circular plastic discs with various functional layers, generally constructed of polycarbonate. The proliferation of optical disc has become extensive. In addition, in recent years, recordable or writable compact discs have grown in popularity. Further, these discs have been used for archival data storage, immediate distribution of data and for many demonstration purposes.
Due to the popularity of optical discs, whether writable or read only, users find that they have more and more optical discs. Therefore, management of optical discs becomes a difficult job. Moreover, optical discs have very large data memory size, that is, users have to put identification on each disc to tell what data has been stored in the disc. Users may also value the ability to place customized graphics on each disc.
With large numbers and mass marketing, discs can be screen printed to place the content information on company logos and alike on the non-writable/readable surface of these optical recording media.
However, for single users or for small runs of discs, screenprinting is generally too cost prohibitive to be useful. Although ink marks may also be used to label discs, it is unattractive and can cause damage to the disc by scratching on the reflective layer during writing on the disc. Another known method of labeling a disc employs a direct printing using an ink jet system onto the disc surface. These systems provide a special carrier for the disc, which is printed using a conventional ink jet printer. Like direct hand marking, this method could damage disc by scratching disc surface, especially for discs lacking scratch resistance (bare discs without prelabels). Furthermore, this method may also bear ink smudging and running problem.
Labeling discs with adhesive labels seems to be the best way to identify the discs, including both content information and personal identity.
Many types of pressure sensitive adhesive (also referred to as “PSA”) labels are known, including those are described by Satas (see Handbook of Pressure Sensitive Adhesive Technology, 3rd edition, D. Satas, 1999). Pressure Sensitive Adhesive labels for optical discs are also known. The disc labels have pressure sensitive adhesive precoated on one side, protected, and delivered with silicone release liners.
Typically, disc labels have same shape (circular shape) and slightly smaller dimensions than the disc needing to be identified. They could be put onto a disc and hand-marked on the label to identify the disc. Even so, a single user may prefer to select a printable CD label and using appropriate software would configure such a label and print the CD label using a printer such as an inkjet printer or laser printer so that personalized information can be professionally put onto a disc.
The challenge arises when a user has to put a pressure sensitive adhesive label onto a disc. Unlike conventional die-cut PSA labels for pricing, product identity, office and inventory information, and stamps, disc labels must be precisely positioned onto a disc. The ring structure of a disc label has to be well positioned on top of the ring structure of the disc. Mispositioning a label on the disc will not only result in poor appearance but may also cause a disc unbalance. Playing (or spinning) an unbalanced disc could further damage the disc (through scratching) or even damage the disc player.
One way to prevent a disc label from being misaligned is to use an alignment device, such as those disclosed in U.S. Pat. Nos. 6,196,290; 6,189,590; 6,168,841; 6,148,891; 5,715,934; and EPO 1015326; EPO 0855712; and JP11255223, but this requires additional devices. U.S. Pat. No. 5,715,493 disclosed a self-guiding disc label having a proper configuration that allows the label to be aligned on a disc by guiding the label with a jewel case. Although this eliminates the use of any additional or special devices, placing a sticky label onto the device or a jewel case loaded with a disc is still difficult for the user because such a sticky backside of the label tends to stay on user's fingers rather than on a device, thus making it unwieldy to position the label.
Regardless of the currently available means of placing a CD label onto a CD, there still remains the fact that the adhesive on a majority of CD labels is a permanent, often aggressive adhesive layer. Thus, when one is placing a label, the user must get it right the first time or else.
Removable labels (as disclosed in U.S. Pat. No. 5,316,344) can be adhered and stay firmly in place and generally will remove cleanly. However, they are generally not repositionable, which means they are not reusable. Such removeability, while it allows the user to remove the label, damages the label, either by removal stress or by curl, and thus the user cannot remove the label and replace the label for alignment.
Typically, conventional labels, whether using permanent or removable adhesive layers, including labels for optical discs, are delivered and packed with silicone release liners.
Therefore, there is a great need to have a repositionable and reusable disc label, which allows a user to position the label to the disc without using any additional alignment devices or configurations. It is also a great desire in industry to make linerless labels.